PI3K-AKT Signaling

Cells respond via phosphoinositide-3-kinase (PI3K) and AKT signaling to a variety of cytokines, G protein coupled receptor ligands, and growth factors as well as to cellular stresses, including heat shock, hypoxia, and oxidative stress. Receptor activation recruits PI3K to the inner cell membrane via phosphorylated receptor tyrosine kinases, activated RAS, or G protein beta and gamma subunits. The enzyme catalyzes the phosphorylation of phosphatidylinositol-3,4-bisphosphate (PIP2) to phosphatidylinositol-3,4,5-triphosphate (PIP3). This lipid anchors AKT protein kinase family members to the membrane for phosphorylation and activation by PDK1. PTEN phosphatase antagonizes PI3K-AKT signaling by converting PIP3 back to PIP2. PI3K-AKT signaling inhibits apoptosis and regulates cell growth, survival, and proliferation, particularly in cancer and tumor cells. For example, unrestrained lymphocytic PI3K-AKT signaling can lead to leukemia and lymphomas, while impaired signaling contributes to anemia and immunodeficiencies. In addition, PI3K-AKT signaling increases synaptic transmission and promotes neuroprotection, and facilitates recovery from ischemia and reperfusion injury in cardiomyocytes. Analyzing the expression, regulation, and sequence of PI3K-AKT genes can help determine their relative importance to the biology of the cellular or disease processes under study and further explore their roles in cell biology. ...

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Cells respond via phosphoinositide-3-kinase (PI3K) and AKT signaling to a variety of cytokines, G protein coupled receptor ligands, and growth factors as well as to cellular stresses, including heat shock, hypoxia, and oxidative stress. Receptor activation recruits PI3K to the inner cell membrane via phosphorylated receptor tyrosine kinases, activated RAS, or G protein beta and gamma subunits. The enzyme catalyzes the phosphorylation of phosphatidylinositol-3,4-bisphosphate (PIP2) to phosphatidylinositol-3,4,5-triphosphate (PIP3). This lipid anchors AKT protein kinase family members to the membrane for phosphorylation and activation by PDK1. PTEN phosphatase antagonizes PI3K-AKT signaling by converting PIP3 back to PIP2. PI3K-AKT signaling inhibits apoptosis and regulates cell growth, survival, and proliferation, particularly in cancer and tumor cells. For example, unrestrained lymphocytic PI3K-AKT signaling can lead to leukemia and lymphomas, while impaired signaling contributes to anemia and immunodeficiencies. In addition, PI3K-AKT signaling increases synaptic transmission and promotes neuroprotection, and facilitates recovery from ischemia and reperfusion injury in cardiomyocytes. Analyzing the expression, regulation, and sequence of PI3K-AKT genes can help determine their relative importance to the biology of the cellular or disease processes under study and further explore their roles in cell biology.